The New South Wales Government has ruled out allowing terminally-ill people to legally use cannabis to help deal with pain.

In May, a cross-party parliamentary committee unanimously recommended allowing terminally-ill patients and people with AIDS to legally use up to 15 grams of marijuana for medicinal purposes.

But the Government has rejected the recommendation, saying there is limited evidence about the efficiency of cannabis for medical purposes and it does not support the use of unregulated cannabis products.

The committee running the inquiry included three Coalition members.

Greens MP John Kaye, who was also on the committee, says the Government's decision is narrow-minded.

"I'm deeply disappointed that the O'Farrell Government has buckled to cannabis use hysteria when they had a perfect opportunity to bring some relief to the pain and suffering of terminally-ill patients," he said.

"This is not about spreading cannabis use, it was about those people who were in terrible pain, who are at the end stage of their lives.

"The O'Farrell Government has turned their back on some patients in New South Wales who are suffering terribly."

Former state Labor MP Paul O'Grady, who is HIV positive and has had cancer treatment, says a trial should have at least been considered.

"Good public policy should be based on evidence, you need in my view, to have trials of these sorts of things so that you can develop the evidence," he said.

"It's not to say that everything works for everyone - whether it was acupuncture for me with neuropathy or whether it's marijuana for pain relief and appetite activation.

"It's about using what tools you have in the box to the best possible advantage."

The Government says it does support the use of prescription pharmaceutical cannabis products approved by the Therapeutic Goods Administration.

It has also committed to writing to the Commonwealth to see if it will allow more patients to gain access to approved cannabis pharmacotherapies, if their existing pain management is not effective.

No synthetic or natural forms of cannabis have been legalised for medical or recreational use in Australia but a synthetic aerosol form of the drug known as nabiximol is being currently being trialled in four Australian hospitals.

In its written response to the committee's report, the Government has also highlighted its Pain Management Plan 2012-2016 and some the initiatives to increase services.

Mr Kaye argues that raising that point avoids the difficult question of using cannabis.

"Pain management clinics are great, they're a big step forward but they don't remove the need to help people who have end stage HIV or terminal cancer and it doesn't avoid the question of how they could have been helped by giving them access to raw cannabis" he said.